1. Blow into the plastic bag and quickly seal it to create a puffed-up bag air.
2. Cover one ear with your hand and the other ear with the bag of ear. 3.
3. Have an assistant tap the bag with a pencil.
4. How does it sound?
5. Now fill the bag with water and seal it.
6. Hold this water-filled bag against one ear while covering the other ear with your hand.
7. Have your assistant tap this bag with a pencil. 8. How does it sound? Finally hold a wooden block over one ear while covering the other ear with your hand.
9. Have your friend tap the block with the pencil.
10.How does it sound?
Compare and discuss your observation.​